1. Field of the Invention
The invention is related to a gliding apparatus for alpine skiing, the apparatus including a binding interface device and a ski that is specifically adapted to receive such a device. The invention is also related to a ski considered independently of the device.
According to the invention, the gliding apparatus and the ski are adapted to a receive one of the skier""s feet and, therefore, they are intended to be used in pairs.
2. Description of Background and Relevant Information
According to the Patent Application published as WO 96/35488, an interface device having an elongated plate on which the two retaining elements are mounted, is known. The plate is raised with respect to the ski. It is connected to the central portion of the ski by two pins whose spacing can be adjusted. Furthermore, a shock absorption element is interposed between each of the ends of the plate and the ski.
Such a device produces a greater concentration of pressure in the central zone of the ski. In addition, in view of the fact that the two retaining elements are mounted on a single plate, separate from the beam of the ski, the ski is freed from the stresses generated by the boot retaining elements.
This interface device provides satisfactory results; indeed, it allows the ski to bend naturally, and while executing turns, the ski follows its path in a natural curve, especially in case of skis having heavily cambered side cuts. But at high speeds, it causes the ski to float somewhat because the plate is only retained on the ski along a short length. Additionally, the ski is free along a greater length towards the front and rear, as compared to a traditional ski, precisely because of the plate connection method. As a result, the ski is more sensitive to vibrations caused by the relief of the terrain, and the plate acts like an insulating element between the boot and the ski.
French Patent Application No. 98/02868 proposes a solution to improve the conditions in which the boot steers the ski, especially aiming to provide a smoother steering of the ski in alternating wide and tight turns. Thus, the application is related to an interface device equipped with a plate, with a front portion being a mounting zone provided for a front retaining element, a rear portion with a mounting zone provided for a rear retaining element, a non-extensible connection being present between the two front and rear portions. On each side of each portion it has a lower wing which is set back with respect to the end of the plate portion, the wing being provided to be pressed against a side wall of the ski, and each wing having a single journal element for affixing the wings to the ski.
One drawback of this type of device is due to the fact that it is attached to the sides of the ski. Indeed, the ski has its own distribution of thickness which depends on the stiffness that it must impart. The insertion of journal elements having substantial diameters has the effect of making the ski structure fragile in certain areas in which the thickness is relatively small.
Another drawback is due to the fact that the supports are transmitted from the plate along the ski through a very specific connection zone, thereby resulting in the inadequate distribution of substantial stresses along the ski surface.
It has also been recognized that the results of the device could be improved by adapting the characteristics of the ski to the device; in particular, by controlling its thickness distribution, and therefore its stiffness, so that the device becomes more efficient.
It is an object of the invention to provide a ski for alpine skiing, the ski having a central zone provided to receive the boot retaining elements. In the central zone of the ski, the ski has two longitudinally spaced zones of increased thickness in which the top surface of the ski has a convex shape due to the progressive variation in its thickness, consisting of an undulation in which the ski thickness increases and then decreases progressively.
Another object of the invention is to provide a gliding apparatus consisting of a binding interface device connected to a ski, the device including:
a front plate having a mounting zone provided for a front retaining element, a rear plate with a mounting zone provided for a rear retaining element, each plate being extended along each side edge of the ski by a lower wing, and for each wing there being a journal element for affixing the wings to the ski.
The ski of the gliding apparatus has, along at least a portion of its width, a localized increase in thickness in two longitudinally spaced zones of the binding interface device that corresponds to the affixing of the journal elements.